贵州喀斯特地区县域耕地资源安全问题探讨——以仁怀市为例

贵州喀斯特地区是典型的生态环境脆弱地区,人多地少矛盾突出,耕地资源安全问题日益引起学界重视.通过研究分析,剖析了仁怀市耕地资源安全态势.应用马尔科夫链预测方法,对仁怀市土地利用变化未来发展趋势进行了定量预测,结果显示:从2005年到2025年,仁怀市耕地面积共减少17177 hm2,年平均减少约687 hm2.到202...     

马尔可夫链在经济预测上的应用

本文将马尔可夫链引入到经济学中 ,通过建立产品的状态转移概率矩阵 ,利用马尔可夫链进行分析和计算 ,给出产品的市场预测、利润预测及风险决策的数学模型 ,从而给经济预测提供切实可靠的理论依据。     

我国城市化进程中的农村集体土地产权制度创新研究

由于受现行土地管理法的约束,我国农村集体土地在城市化进程中不能享有与国有土地同等的权利,不仅所有权得不到尊重、使用权受到严格限制,而且土地的主人农村集体和农民个人的土地权益也得不到合理补偿,由征地引发的社会矛盾日益尖锐。为探索保障农村集体土地权益的有效途径,缓解社会矛盾,我国的农村集体土地产权制度必须创新。从尊重现行土地管理法的思路出发,对广大农村和城市化进程中的农村集体土地采取不同的政策,只能是权宜之计,而从尊重农民集体土地所有权的思路出发,变土地管理法主要是约束农民集体行为为约束政府的征地行为,才是最终之本。     

人民币汇率形成机制改革方式研究

文章分析放弃人民币盯住美元汇率制度的理由,阐述人民币汇率制度不具备实行单独浮动的条件,也不宜使人民币完全盯住一篮子货币,中国人民银行公告以市场供求为基础的、参考一篮子货币进行调节、有管理的浮动汇率制度是可行的.     

Price relationships between qualitatively differentiated agricultural products: organic and conventional wheat in Germany

Organic agriculture, which produces commodities that can be qualitatively differentiated from conventional food products, has grown into an important market in many countries. The dynamics of commodity prices in both sectors are partly interdependent, but are also shaped by independent determinants and have rarely been studied. We analyze organic food markets and their interdependencies with conventional markets in the context of wheat markets in Germany, which have been subject to a number of fundamental changes during the last two decades. Based on institutional market characteristics, we suggest a flexible Markov‐switching asymmetric time series model. We find a pronounced temporal sequence of market phases that differ in their asymmetric dynamics and the extent to which the organic price is influenced by the conventional price. Organic wheat prices tend to be increasingly connected to prices of conventional wheat.     

基于景观生态学的区域土地利用结构演变及优化分析——以北京市顺义区为例

从景观生态的角度对北京市顺义区1996-2006年的土地利用结构演变进行数量与空间特征变化分析,并借助马尔科夫模型进行用地预测,获得该区土地利用演变规律:顺义区地类的面积比例呈现出均一化的特点,耕地和未利用地的数量减少,建设用地、生态用地和廊道增加,且建设用地将在10a之内代替耕地成为该区域的优势景观类型,而生态用地、廊道与未利用地将维持一个相对稳态;空间层面上,研究区整体景观的破碎度增加,聚集度减少,景观形状呈现简单化,景观异质性和多样性增强。最后,以"斑块-廊道-基质"理论为依据,构建出顺义区土地利用结构优化框架:即集中耕地形成基质,斑块的布局应该特别注重生态节点的建设和生态敏感地带的保护及建设生态廊道。     

Empirical Bayes analysis of log-linear models for a generalized finite stationary Markov chain

This article presents the empirical Bayes method for estimation of the transition probabilities of a generalized finite stationary Markov chain whose ith state is a multi-way contingency table. We use a log-linear model to describe the relationship between factors in each state. The prior knowledge about the main effects and interactions will be described by a conjugate prior. Following the Bayesian paradigm, the Bayes and empirical Bayes estimators relative to various loss functions are obtained. These procedures are illustrated by a real example. Finally, asymptotic normality of the empirical Bayes estimators are established.     

Testing for negativity in a demand system: A Bayesian approach

The paper introduces Bayesian inference into a demand model. This allows us to test for the negativity condition of the substitution matrix which is difficult to handle directly in the traditional approach. To illustrate the Bayesian inference procedures, we estimate the Rotterdam model and test the demand properties using Japanese data. The empirical results show the importance of specifically considering negativity in demand analysis. First version received: September 1997/final version received: February 1998     

探索土地问题的解决途径

从历史上看,农民的增收问题从来都是同土地产权制度的安排以及如何使用紧密联系在一起的。新中国成立以来,农地制度经历了四次重大变革。从变革中可以看出,土地问题确实是解决"三农"问题的核心。土地问题的解决不可能是一劳永逸的,现实中的问题只能通过改革来解决。     

中国省际城镇职工工资收入分布演进的时空特征

运用Kernel密度估计方法和空间马尔科夫链分析方法,并将空间因素纳入分析框架中,对1978—2009年期间中国省际城镇职工工资收入分布演进的时空特征进行了分析。研究结果表明:从时间动态性看,中国省际城镇职工工资收入的差距正逐步固化和深化,多俱乐部收敛特征明显、贫困陷阱问题日益突出;从空间动态性看,近邻效应对省际城镇职工工资收入分布演进存在一定影响,多数省份的工资收入水平向邻区的平均工资收入水平演进。